﻿using Nintemulator.Shared;
using word = System.UInt16;

namespace Nintemulator.SFC.GPU
{
    public partial class Gpu
    {
        public static int[][] ColourLookup = Utility.CreateArray<int>( 16, 0x8000 );
        public static byte[] ReverseLookup = new byte[]
        { 
            0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0,
            0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8,
            0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4, 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4,
            0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC,
            0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2,
            0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA,
            0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6,
            0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE, 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE,
            0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1, 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1,
            0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, 0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9,
            0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, 0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5,
            0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED, 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD,
            0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3,
            0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB,
            0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7, 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7,
            0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF
        };

        internal byte cram_data; // latch for cgram
        internal word cram_addr;
        internal byte oram_data; // latch for oram
        internal word oram_addr;

        internal Register16 vram_addr;
        internal MemoryChip cram = new MemoryChip( 0x0200u ); // 256x15-bit
        internal MemoryChip oram = new MemoryChip( 0x0220u ); // 256x16-bit + 16x16-bit
        internal Register16[] vram = new Register16[ 0x8000u ]; // 32kw

        internal byte vram_ctrl;
        internal byte vram_step = 0x01;

        private uint MapVRamAddress( uint address )
        {
            switch ( ( vram_ctrl & 12u ) >> 2 )
            {
            default: return ( address & 0x7fffu );
            case 1u: return ( address & 0x7f00u ) | ( ( address & 0x00e0u ) >> 5 ) | ( ( address & 0x001fu ) << 3 );
            case 2u: return ( address & 0x7e00u ) | ( ( address & 0x01c0u ) >> 6 ) | ( ( address & 0x003fu ) << 3 );
            case 3u: return ( address & 0x7c00u ) | ( ( address & 0x0380u ) >> 7 ) | ( ( address & 0x007fu ) << 3 );
            }
        }

        public void Poke2121( uint address, byte data )
        {
            cram_addr = ( ushort )( data << 1 );
        }
        public void Poke2102( uint address, byte data ) { oram_addr = ( word )( ( oram_addr & ~0x1feu ) | ( ( data & 0xffu ) << 1 ) ); }
        public void Poke2103( uint address, byte data ) { oram_addr = ( word )( ( oram_addr & ~0x200u ) | ( ( data & 0x01u ) << 9 ) ); }
        public void Poke2116( uint address, byte data ) { vram_addr.l = data; }
        public void Poke2117( uint address, byte data ) { vram_addr.h = data; }

        public byte Peek213B( uint address )
        {
            var data = cram.b[ cram_addr & 0x1ffu ];

            cram_addr++;
            return data;
        }
        public byte Peek2138( uint address )
        {
            if ( ( oram_addr & 0x200 ) != 0 )
            {
                // high table
                return oram.b[ oram_addr++ & 0x21fu ];
            }
            else
            {
                // low table
                return oram.b[ oram_addr++ & 0x1ffu ];
            }
        }
        public byte Peek2139( uint address )
        {
            var data = vram_latch;
            vram_latch = vram[ MapVRamAddress( vram_addr.w ) ].l;

            if ( ( vram_ctrl & 0x80U ) == 0 ) { vram_addr.w += vram_step; }

            return ppu1_open = data;
        }
        public byte Peek213A( uint address )
        {
            var data = vram_latch;
            vram_latch = vram[ MapVRamAddress( vram_addr.w ) ].h;

            if ( ( vram_ctrl & 0x80U ) != 0 ) { vram_addr.w += vram_step; }

            return ppu1_open = data;
        }
        public void Poke2122( uint address, byte data )
        {
            if ( ( cram_addr & 1u ) == 0u )
            {
                cram_data = data;
            }
            else
            {
                data &= 0x7f; // fix games that write $ffff for white

                cram.b[ cram_addr & 0x1feu ] = cram_data;
                cram.b[ cram_addr & 0x1ffu ] = data;
            }

            cram_addr++;
        }
        public void Poke2104( uint address, byte data )
        {
            if ( ( oram_addr & 0x200u ) != 0u )
            {
                oram.b[ oram_addr & 0x21fu ] = data;
            }
            else
            {
                if ( ( oram_addr & 1u ) == 0u )
                {
                    oram_data = data;
                }
                else
                {
                    oram.b[ oram_addr & 0x1feu ] = oram_data;
                    oram.b[ oram_addr & 0x1ffu ] = data;
                }
            }

            oram_addr++;
        }
        public void Poke2118( uint address, byte data )
        {
            vram[ MapVRamAddress( vram_addr.w ) ].l = data;

            if ( ( vram_ctrl & 0x80u ) == 0 ) { vram_addr.w += vram_step; }
        }
        public void Poke2119( uint address, byte data )
        {
            vram[ MapVRamAddress( vram_addr.w ) ].h = data;

            if ( ( vram_ctrl & 0x80u ) != 0 ) { vram_addr.w += vram_step; }
        }
    }
}